| The focus of this dissertation is the study of the placement of luminescent molecules and molecular machines in and on mesostructured silicate thin films. Mesostructured silicate thin films have three distinct and spatially separated regions, (1) the silicate framework, (2) the ionic region comprised of the charged surfactant head groups, the counterions, and residual solvent, and (3) the organic region made up of the hydrocarbon tails of the surfactant. Each of these regions has unique physical and chemical properties that are exploited in order to control the placement of molecules.; Three strategies are used to place molecules in each of these regions. These strategies are succinctly termed "philicity" (or like dissolves like), chemical bonding, and bifunctionality. Single molecules have been placed in each of these regions, and dual placement of luminescent molecules has also been achieved. Ru(bpy)32+ and diheptyl methylviologen are a well known donor acceptor pair that were simultaneously placed in a mesostructured film. Luminescence and lifetime measurements suggest that there is electron transfer, but further studies must be conducted to determine the exact placement of the diheptyl methylviologen.; The study of the incorporation of azobenzenes with large dendritic groups into mesostructured silica thin films via two different strategies, the bifunctional strategy and the philicity strategy is reported. The study shows how it is possible to follow the isomerization by fluorescence. There are several possible applications such as using the azobenzene dendrimers as gates for a nanovalve, or for sweeping small molecules through mesoporous rods or for electron or energy transfer. Various azobenzenes were studied and the results documented for the support of the ongoing project.; Supramolecular machines have been very well studied in solution but have never been studied on silica films. A functioning nano-machine in the form of a supramolecular nanovalve (pseudorotaxane) that opens and closes the orifices to molecular-sized pores, made by templating a sol gel silica thin film, and releases a small number of molecules on demand is reported. The release of the molecules is monitored by luminescence. Two-stage rotaxanes, that can act as pistons were tethered to the surface of a silica film and the motion also studied by luminescence. |
